1. Field of the invention
The present invention relates to a dye ribbon package for use with a thermal printer which comprises a supply spool with a roll of dye ribbon wound thereon and a take-up spool having the leading end of the dye ribbon attached thereto, and to a method of loading the reloadable cassette of a thermal printer with the dye ribbon from the described package.
2. Description of the prior art
In a typical color thermal printer, a dye ribbon in the form of a web-type dye-carrier containing a series of spaced frames of different coloured heat transferable dyes is spooled on a supply spool. The ribbon is unwound from the supply spool and rewound on a take-up spool. The ribbon moves through a nip formed between a thermal print head and a dye-absorbing receiver sheet. The receiver sheet may, for example, be coated on synthetic paper and the print head is formed of a plurality of heating elements. When heat is supplied to the dye ribbon, dye is transferred to the receiver sheet.
At the beginning of a print cycle, the receiver sheet must .be clamped to the drum of the printer which is at a home or starting position. After being clamped to the drum, the receiver sheet is advanced under the print head. The heating elements of the print head are energised to form a dye image. The drum makes several revolutions as different coloured dye images are applied into the receiver sheet. In this way, a final, full-coloured image is produced. Thereupon, the clamp of the drum is opened and the receiver sheet is ejected from the thermal printer. The drum then advances the clamping mechanism back to the home position and the above-mentioned process is repeated.
The dye ribbon is difficult to handle since it has typically a thickness in the order of magnitude of ten micrometers only, in order not to impede the heat transfer from the heating elements towards the receiver sheet. For that reason, the supply spool and the take up spool are usually provided in a dedicated cassette which has a central rectangular opening for allowing the print head to urge the ribbon in contact with the receiver.
Known cassettes are made from plastic and are of the disposable type so that convenience for the operator of the printer is high. Since environmental considerations are placing an ever increasing strain on the use of disposable cassettes, there is a recent trend to use reloadable cassettes. These reloadable cassettes have basically the same configuration as the original dedicated ones but have a two part construction allowing the operator to open them and to load them with a supply spool with a roll of fresh dye ribbon and an empty take up spool. The loaded cassette is then put in the printer in the same way as an original disposable cassette.
The difficulty with the described reloading procedure resides in the manipulations that are required to remove the supply spool and the take up spool from the package in which they are wrapped by their manufacturer in order to load them in an empty cassette. In a known packaging form, the supply spool and the take-up spool are wrapped closely together in a bubble foil that is kept closed by self-adhesive tape, which package is wrapped in a rigid rectangular cardboard box.
Removal of the bubble foil and gripping of the spools to insert them in the cassette inevitably brings the operator's hands in contact with the thin dye ribbon which is extremely vulnerable and can be damaged by wrinkling and even by mere skin contact.
A thermal printer and a dye ribbon cassette for use therein are disclosed e.g. in U.S. Pat. No. 4,815,870 and 4,915,516.